1. Field of the Invention
This invention relates to a surgically implantable device for use in mixing blood and for treatment of conditions such as hypertension. In particular a device according to the invention may be used to reduce hypertension of a cirrhotic liver.
The liver is connected to the vascular system through the hepatic artery and a portal vein on its proximal side and through a hepatic vein on its distal side. The hepatic artery and portal vein merge within the liver to provide the blood flow for the hepatic vein.
Hypertension of the liver, for instance in a cirrhotic liver, or in the case of hepatitis, is a serious health problem. Although there exists a pharmacology for partially treating liver hypertension, no way exists as yet for reducing the amount of work the liver must perform and allow the liver to repair itself.
In the treatment of some pathological conditions of some organs, it is desirable to alter the blood flow patterns to an organ, particularly to the liver. For example, it is believed that a high volume of arterial flow to the liver may be a block to portal flow to the liver. A blockage in portal flow to the liver is believed to cause a diversion of blood flow around the liver such that the blood from the stomach is not adequately filtered. By increasing the portal flow to the liver and/or decreasing the arterial flow to the liver, it is believed that the normal blood flow can be restored to the pathological liver, which may enable it to heal itself and to regain effectiveness.
There are various applications for a device for mixing, injecting or shunting blood flow. One such application is the so-called porta caval shunt wherein the flow of the portal vein is shunted to one of the vena cava veins.
2. Description of the Prior Art
Until now the joining of blood vessels to mix blood flow has been accomplished by surgically suturing vessels together along a longitudinal incision of one of the vessels. Unfortunately, such a technique provides only limited edge control at the junction of the joined vessels. It is therefore difficult to construct a reliable junction, and such a junction is prone to failure, particularly under pressure from blood flow. In addition, in such a technique, it is not readily possible to control the ratio of mixing of blood or the angle at which blood is injected into mixture.
In general, placing an implant in the body is well known. However, there is no decompression mechanism or similar device for handling in vivo blood flow. Arterialization of the portal vein is known wherein arterial tissue is cleaved to venous tissue and venous tissue is ligated upstream of the junction. No mixing of venous blood has been suggested.